74
E-MU Systems
Programming Basics
Dynamic Filters
Another characteristic of a filter is the number of poles it contains. Tradi-
tional synthesizer filters were usually either 2-pole or 4-pole filters. The B-3
has selectable 2, 4, 6, and even 12th order filters. The higher the order of a
lowpass, highpass or bandpass filter describes the steepness of its slope. The
higher the order (another word for the number of poles), the steeper the
filter's slope and the stronger the filtering action. The tone controls on your
home stereo are probably one-pole or two-pole filters. Parametric equalizers
are usually either two-pole or three-pole filters.
In terms of vintage synthesizers, Moog and ARP synthesizers used 4-pole
filters, Oberheim and E-mu synthesizers were famous for their 2-pole filter
sound.
Of course B-3 contains far more filtering power than most synthesizers. In
one of B-3’s complex 12th order morphing filters, there may be several
peaks and dips which change according to the filter frequency parameter.
For these filters, think of the order as the complexity of the filter.
_
_
_
_
Important:
12th order
filters use twice as many voices!
B-3 has the processing power to produce 64 filters of up to 6th order or 32
filters of 12th order complexity. Therefore, if you decided to use all 12th
order filters, B-3 would be limited to 32 voices.
Using a filter, we have a way to control the harmonic content of a sound.
As it turns out, even a simple low-pass filter can simulate the response of
many natural sounds.
For example, when a piano string is struck by its hammer, there are initially
a lot of high frequencies present. If the same note is played softer, there are
fewer high frequencies generated by the string. We can simulate this effect
by routing keyboard velocity to control the low-pass filter. The result is
expressive, natural control over the sound.
If you use an envelope generator to control the cutoff frequency of a filter,
the frequency content can be varied dynamically over the course of the
note. This adds animation to the sound as well as simulates the response of
many natural instruments.
Frequency
Amplitude
4-pole
Lowpass
6-pole
Lowpass
2-pole
Lowpass
Summary of Contents for B-3
Page 1: ...64 Voice Tone Wheel Organ OPERATION M A N U A L ...
Page 136: ...128 E MU Systems Edit Menu Play Solo Layers ...
Page 148: ...140 E MU Systems Programming Tutorial Linking Presets ...
Page 170: ...162 E MU Systems Save Copy Menu Copying Information ...